Known in the art is an internal combustion engine designed so that main fuel gas is supplied to an inside of a main combustion chamber, an auxiliary chamber communicating through communicating holes with the inside of the main combustion chamber and having a spark plug is formed on a top surface of the main combustion chamber, auxiliary fuel gas is supplied to the inside of the auxiliary chamber, and, the main fuel gas inside the main combustion chamber is burned by jet flames ejected from the communicating hole when the auxiliary fuel gas supplied to the inside of the auxiliary chamber is made to burn (for example, see Japanese Unexamined Patent Publication No. 2004-36424).